Installation Manual Part 7

FCC ID: CDG-ARTU EXHIBIT C
MAGNASTAR C-2000 DIGITAL AIRBORNE TELEPHONE SYSTEM
9.2.4 L-Band Interference Tests
Because the C-2000 system operates in the 850.900 MHz range, interference between the C.2000 and L-
Band equipment (i.e. DME, Transponder, TCAS) can occur if there is not enough isolation between
antennas. Testing for interference can be done by making the C-2000 equipment transmit. By monitoring
the Receiver Signal Strength (RSS) value reported in the Radio Status screen while the ARTU is
transmitting, it can be determined if the L-Band equipment interferes with the C-2000 system.
The simplest test method is to use the MMTI installation test mode and to stop at the Receive Signal
Strength test step. By not connecting up the loop around test box, no signal level should be reported above
the nominal no signal value. Frequency agile devices like DMEs must be tuned and transmit across the
whole operating frequency range to assure that there are no frequency dependent interference problems. If
any change occurs in the RSS value then there is interference from external equipment. The nominal no
signal value of the RSS can be determined by disconnecting the receive coax cable from the ARTU and
viewing the RSS value on the Radio Status screen. See section 6.3.12 for the Receive Signal Strength
Measurement test procedure.
9.2.5 CEPT -El Communication Verification
The MagnaStar ARTU is capable of interfacing to multichannellNMARSA T SA TCOM equipment using a
CEPT -EI digital interface. ARTU part number 724855-802 has additional hardware which will support
this interface. Calls are routed through the ARTU to the SA TCOM over the CEPT -E I interface. The
CEPT -E I interface is a 2.048 MHz time division multiplexed data bus consisting of differential serial
transmit and receive lines.
Communication between the ARTU and the SA TCOM equipment can be verified by viewing a MagnaStar
digital handset. If a handset displays the word Satcom on the Services menu when the handset is on hook.
or in the bezel, then the ARTU and SA TCOM equipment are in communication over the CEPT -E I
interface. Also, if the LINK option is available from the handset Main menu, then the CEPT-EI is
operational. If SA TCOM is not present at the Services menu, then the SA TCOM system has informed the
MagnaStar system there are no channels available. If this happens during initial system installation, verify
the Satcom system configuration jumpers (verify that the SA TCOM system has been configured for
External CTU). It is possible that conditions may exist which will keep SA TCOM calls from being placed
SA TCOM units do provided status information to the ARTU over the CEPT -E I bus which can indicate that
the SA TCOM unit is either faulted or that SA TCOM channels are not available for use. This information is
reported to the user when a call is placed. SA TCOM channels not being available for use may include
items beyond the SA TCOM unit including satellite coverage problems or ground station problems.
It is possible to detennine the status of the CEPT -EI interface between the ARTU and the SATCOM unit
using the MMT. Figure 9.2.5 shows the ARTU Status screen. In the lower right hand comer is CEPT -EI
status information. The CEPT -EI status information has three possible states; RR, RNR and DOWN.
There are two columns of information. The ARTU column applies to the ARTU and the CMS column
applies to the SA TCOM equipment. It may be possible to isolated RNR problems to a particular piece of
equipment using the column labels.
This status infom1ation means Receiver Ready. This condition indicates that the CEPT.
El interface and equipment is operational.
RR-
RNR - This status information means Receive Not Ready. This condition indicates that the
CEPT -E 1 interface is operational but that the equipment is not functional.
DOWN - This status information means that the CEPT -El interface is not operational. This could
indicated that either piece of equipment is at fault or no CEPT -E 1 connection.
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